Belt tensioning mechanism for conveyers



Nov. 2, 1948.

' J. S. BELTZ BELT TENSIONING MECHANISM FOR vCONVEYERS 3 Seats-Sheet 1Filed July 20, 1945 JOHN S. BELTZ B-.r/ 5W ATTORNEY Nov. 2, 1948.

J. s. BEL'rz BELT TENSONING HECHANISM FOR CONVEYERS Filed July 2o, 1945v 3 Sheets-Sheet 2 ATTORNEY Nov., 2, 1948. J. s. Bl-:L'rzI 2,452,980

BELT TENSIONING MECHANISM FOR CONVEYERS Filed July 2o, 194s 3Sheets-Sheet' 3 Jol-m s. aslf'rz A TTO RNEY BELT TENSIONING MECHNISM FORCONV EYERS John S. Beltz, Columbus, hic, assigner, by mesne assignments,`to The Jeffrey 'Manufacturing Company, a corporation of OhioApplication July 2o, 1945, serial No. eoazsv iciaims. '(el. 19a-cos) iThis invention relates 'to a conveyor and more particularly to aconveyor wherein the tension of Ithe material carrying device thereof ismaintained substantially constant.

It is an object of my inventionto provide a conveyor in which a belttensioning mechanism and its associated parts are located in theconveyor head member or section.

It is another object of my invention to provide a conveyor that includesin its head member or section a belt tensioning mechanism that appliestension to the belt of the conveyor by means of a pressure device thatis adapted to exert a substantially constant tensioning force upon saidbelt and concomitantly accommodate variations in the length thereof.

In carrying out the foregoing object it is another object of myinvention to train the belt of the conveyor over pulleys or drums in theconveyor head member or section so as to form a loop'therein and tocause the tensioning mechanism to urge one of the pulleys to adjust thelength of the loop in yaccordance with the tension of the belt.

It is yet another object of my invention to provide a conveyor includinga head member or section embodying a pressure operated rbelt-tensioningmechanism adapted to urge -a belt receiving pulley thereof toward a belttensioning'posif tion and to provide means in the head memiber orsection for manuallypositioning the belt tensioning mechanism within itsoperating limits.

, Other objects of the invention will appear hereinafter the novelfeatures and combinations being set forth in the appended claims.

In the accompanying drawings,

'g. 1 is aview in plan of one form of conveyor apparatus that embodiesmy invention;

Fig. 2 is a side view of the conveyor apparatus shown in Fig. 1, certainmechanisms thereof being omitted for the sake of clarity;

Fig. 3 is a side view on a larger scale of a portion of the conveyorapparatus shown in Figs.

1 and 2 and showing the tensioning apparatus for the belt of theconveyor;

Fig. 4 is a view in section, the section being taken substantiallyonline 4 4 of Fig. 3, the view omitting lthe belt of the conveyor for.the-sake of clarity; s

Fig. 5 is a diagrammatic side view of another form of conveyor appartusthat embodies my invention;

are. 5:

Fig. 'i is a view in plan of that portion of the conveyor apparatusshown in Fig. 6. the belt of the conveyor being omitted for the sake ofclarity; and

Fig. 8 is a view in section, the section being taken on line 8-8 of Fig.6.

Referring to the drawings and particularly to Figs. 1 and 2, theconveyor I0 embodied therein has a head mem-ber or section II 4and afoot or tail member or section I2 interconnected by one or moreintermedi-ate sections or members. The head member or section I I lisconstructed about a frame I3 which includes a base or ground engagingskid pan I4. Pairs of oppositely disposed vertical side members I5, I6and Il extend upwardly from the base or ground engaging skid pan I4 andsupport a deck I8 that extends forwardly from above the base or skid panHl and supports a head pulley or drum I9 through suit able anti-frictionbearings which are secured.`

to its outer end. The material carrying device of the conveyor I Il isin the form of ya belt 2| that is trained about the head pulley or drumI9 and about a pulley or drum 22 of the foot or tail member l2. Theupper run 23 of the belt forms the working or material conveying run oithe conveyor I0 and is carried or supported between the head and tailpulleys or drums I9l and 22 by -a plurality of idler rollers 24supported by suitable brackets 25 that extend upwardly from the framemem-bers of the conveyor apparatus I0. The overall height of the headsection I I increases progressively f'orward-ly which with thel overhangof deck I8 provides for ready discharge of material from belt ZI intomine cars or the like which may be positioned Abelow head pulley I9. Thelowerpor return run 26 of the belt 2I extends from the head `pulley ordrum I9 through the-head member or section II of the conveyor l0 and istrained or looped about .pulleys or drums that are lsupported by theframe I3. Foreign substances which might adhere to the belt 2| andinterefere with its operation as it passes over the pulleys or drums ofthe hea-d member or section II are removed therefrom by a belt cleaner4B l carried by the deck I8. From the head member or section il thereturn run 26 of the belt 2| exnected by gears 32 secured thereto andthe pulleys are driven from a power unit 33 that' includes an electricmotor 34 and a speed reducer 36 mounted upon a suitable base 36. Theslow speed shaft 31 of the speed reducer 35 carries a sprocket 38 unit33 is attached. When the length of the conveyor is relatively short itmay be desirable to drive the belt 2| by the pulley 28 only and in suchcase the gears 32 are removed.

The conveyor i0 is particularly adapted for use in coal mines andbecause of the limited spaces in which the conveyor may be required tooperate it is desirable that the gears 32 and power unit 33 betransposable from side to side thereof. To this end the angle members 4|and shafts 30 and 3| extend from both sides of head member il.

The frame i3 of head member il carries a motor unit 43 (see Figs. 3 and4) between two pairs of tubes 42 that extend between the verticalmembers I6 and i1. Motor unit 43 includes a pulley or drum 44. Thevertical frame member i6 also carries a large idler pulley or drum 45through suitable anti-friction bearings.

An important feature of my invention resides in the motor unit 43, itsfunctions and position in the conveyor. The motor unit 43 includes afluid pressure motor 41 that is carried by an adjustable frame 46, theend blocks 49 of which are slidably received between the pairs of tubes42.

The piston shaft 50 of fluid motor all is connected'- to a yoke 5l thatcarries pulley shaft supporting 'slides 52 which support the shaft 63 ofpulley or drum 44 and are adapted to slide rectilinearly in slots 54 inthe end blocks 43 of the frame 48 in a limited range.

The head frame i3 cooperates to provide a rack by which the position ofthe motor unit 43 may be adjusted independently of the motor 41 to bringinto or to position the motor unit frame within 'the operating range ofrectilinear movement of the pulley 44. The members l1 of the frame carrya cross shaft 55 whichl is geared through reduction gearing 56 tosprockets 51, one of which is mounted in each vertical member l1.Sprockets 58 carried by the vertical frame member i6 and sprockets 51carry chains 53, the upper runs of which extend through the upper tubesi2 and the lower runs oi which are connected to the end blocks 43 of themotor unit frame 48. A turnbuckle 68 is interposed in each chain 69adjacent the blocks 49 for tightening them. A handle or lever 8| ismounted on the end of the cross shaft 55 through avreverslble ratchetmechanism 52 for rotating the sprockets 51 and pawls 63 carried byvertical frame members i1 engage the reduction gearing 56 to retain theframe 48' of the motor unit 43 in its adjusted position.

The fluid motor 41 in the present embodiment of my invention ispreferably, but not necessarily, an air motor which is supplied withcompressed air from a motor-compressor unit 64 that is seen in Fig. 1.The motor-compressor unit 84 includes a compressor 65, an electriccompressor driving motor 66 and a suitable compressed air storage orsupply tank 81.. The motor-compressor unit 64 may be any of thewell-known types of such devices wherein a pressure control switch 68 isplaced in the electric current supply lines of the driving motor 66 forstarting and stopping said motor when the pressure in the storage tank81 exceeds or falls below the desired pressure. The cylinder 89 of thefluid motor 41 is connected to the compressed air storage tank 81through a pressure reducing valve 10 that is adapted to deliver airunder constant pressure to the uid motor 41 regardless of fluctuationsof the pressure in the supply tank 61.

As seen in Fig. 2 of the drawings, the belt 2| is trained from the footpulley 22A over the top of the conveyor I0 to the head pulley I9 andfrom the head pulley I9 over the driving pulleys 29 and 28. From drivepulley 28 the return run 26 of the belt is led over the uid motor unitpulley 44 to idler pulley 45 and to the foot or tail pulley 22.

`In operation the belt 2| is driven in the direction of the arrow seenin Fig. 2 by the power unit 33 through driving pulley 28 or pulleys 28and 29 if the gears 32 are utilized. The motor-compressor unit 64supplies air through pressure reducing valve 10 under constant pressureto the fluid motor 41 which causes the yoke 5| and pulley or drum 44 tomove in a belt tensioning direction which in the conveyor l0 is towardthe foot or tail member or section i2. Movement of the pulley or drum 44toward the foot or tail member or section l2 applies tension to the belt2| by increasing the length of the loop in the return run 26 that isformed by the pulley 44 between thel driving pulley 28 and the idlerpulley 45.

In conveyors that are adapted for use in confined spaces such as in coalmines for example,

it is important that the height of the conveyor be maintained at aminimum and this I accomplish by causing the belt takeup loop betweenthe pulleys 28 and 45 to lie within the head member or section and insubstantially the same plane as the main runs of the conveyor belt'2l.The

e@ placing of this automatic belt tensioning mechanism in the headsection is of importance, particularly in long conveyors, since it isadjacent.

the driving motor and room entry, and thus readily available,particularly for `adjustment of the unit' 43 by the hand lever 6I. Alsothe head section inherently or normally hasV increased height, thusreadily accommodating such automatic takeup without increasing thenormal height of the conveyor.

The length of such conveyors frequently reaches three thousand feet,therefore since the length of belts suitable for such long conveyors issubject to change for various reasons, such, for example, as variationsin the load carried, changes in temperature, and the like, it isimportantl that the belt be free to expand and contract and yet beretained under a substantially constant tension to prevent slipping atthe driving pulleys or undue stretching of the belt.

The operating l'mits of motor unit 43 are de termined by the lengthofthe slots 54 in which the pulley supporting slides 52 function. Inorder to accommodate. considerable lengthening of the belt 2| as it isused the position of the motor unit 43 is adjustable along the supporttubes 4'2 through the reversible rack mechanism described and the motorunit 43 is adjusted manually to such position that the slides 52 arewell within l :incasso of the belt V 2l while concomitantly maintainingthe belt; yunder a lconstant tension; shcuidthe tension on the-beltincrease, the iluid motor 41 yields to permit4 the pulley 44 'to move toaccommodate the necessary change in length of the takeup loop to retainthe. belt under a 'substantially constant tension. Should fluid motor orcylinder All lbecome completely expanded or contracted, the unit orcarriage i3 may be adjusted by hand lever 6I so the automatic ten- 'ingfor a longer stroke.

The takeup loop of the conveyor belt is formed between an idler pulley'il and the foot or tail pulley 'i2 by a pulley i3 that is moved towardthe head pulley lli, to tighten the conveyor belt W. by a pair of fiuidmotors 'i5 that are of the piston type.

In this embodiment the full adjustment of the size of the takeup loop inthe belt is accomplished by the fluid motors 'i5 which are of suchlength as to accommodate belt loops from the minimum to the maximumdesirable lengths.

A portion of another head member or conveyor section is shown in Figs.6, 7 and 8. This head section includes supporting skids i6 froirnv whichvertical side members 1l extend upwardly to support a deck 'i8 thatincludes channeled side members 19. In this embodiment the belt takeuppulley i3 is 4carried by a rack or sliding frame 80 that slides onchannel members 19 of the head section frame and is moved toward thehead .pulley Bl by the pair of uid -motors 'l5 to keep the .belt underpredetermined tension, it being understood that the fluid motors are ofthe single acting type and receive air under substantially constantpressure from a motor-compressor unit 6d' and that the head member orsection of the conveyor l i0 includes belt driving pulleys I 28 and 29which are driven by a power unit 33. The

takeup loop in the conveyor belt is formed be tween an idler pulley 'liof the head member or section and the tail pulley i2 by the takeuppulley i3 and the takeup loop of the belt lies below and in the samegeneral direction as do the main runs of the conveyor belt. While thearrangement oi parts of the embodiments shown differ, their operation inmaintaining the conveyor belt under substantially constant. tension issimilar. The convey-or of Figs. 5 to 8, inclusive, like the conveyor ofFigs. l through 4, has its belt takeup or tensioning mechanism in itshead section, the desir-able fes tures of which are above pointed out.

The conveyor embodied in Figs. 1 through 4 shows the belt ti in thematerial conveying or working run 23 as being fiat and the conveyorshown in the embodiment of Figs. 5 through 8 shows the belt in thematerial conveying or working run as being troughed. It is to beunderstood that the belt in the material conveying or working run ofveither conveyor may be dat or troughed asdesired.

Obviously those skilled in the yart may 4make various changes in tthedetails and arrangement of parts without departing from the spirit andscope of the invention as defined by the claims' -hereto appended and Iwish therefore not to be Likewise,

restricted -to the precise construction herein disclosed.

Having thus described and shown an embodtment of my invention. what Idesire to secure by Letters-:Patent.oi Vthe United States is:

l'. A head section for a conveyor including a main frame having abeltreceiving pulley over which material is to be discharged, a pair ofpower driven belt driving pulleys mounted in said main frame rearwardlyci said discharge pulley, an-

other pair of belt receiving pulleys mounted in said main frame andlocated rearwardly of said power driven pulleys, a frame within saidmain frame mounting one of said last named pulleys for rectilinearmovement in a limited range, huid pressure means carried by said frameforI urging said movable pulley in a belt tensioning direction, saidpairs of pulleys all being located below the top of said head sectionmain frame and between the sides thereof, and means for manuallyadjusting rectilinearly the position oi said frame independently of saidfluid pressure means for positioning it within the operating range oirectilinear movement of said pulley.

2. A head section for a conveyor including a main frame having a beltreceiving pulley over which material is to be discharged, a pair of beltreceiving pulleys mounted in said main frame and located rearwardly ofsaid discharge pulley. a framewithin said main frame mountingl one ofsaid last named pulleys for rectilinear movement in a limited range,duid pressure means carried by said frame for urging said movable pulleyin a belt tensioning direction, said pair of pulleys being located belowthe` top of said head .section mainframe and between the sides thereof,and

-means` for manually adjusting the position of said frame independentlyof said iluld pressure means for positioning the frame' within theoperating range of rectilinear movement of said pulley. l

3. A conveyor including a head section and a V4tail section, said headsection including a main frame having a belt receiving pulley over whichmaterial is to be discharged, a pair of power driven belt drivingpulleys mounted in said main frame rearwardly of said discharge `pulley,another pair of belt receiving pulleys mounted in said main frame andlocated` rearwardly of said power drivenpulleys, a frame within saidmain frame mounting one of said last named pulleys for rectilinearmovement in a limited range, fluid pressure means carried by said framefor urging said movable pulleyin a belt tensioning direction, said pairsof pulleys all being located below the top of said head section mainframe and between the sides thereof, and means for manually adjustingrectilinearly the position of said frame independently of said 'fluidpressure means for positioning it within the operating range of recti-A.

linear movement of said pulley.

4. A conveyor including a head section and a tail section, said headsection including a. main frame having a belt receiving pulley overwhich material is to be discharged, a pair of belt receiving pulleysmounted in said main frame and located rearwardly of said dischargepulley, a frame within said main frame mounting one of said last namedpulleys for rectilinear movement in a limited ran-ge, iluid pressuremeans carried by said frame for urging said movable pulley in a belttensioning direction, said pair of pulleys being located below the topof said head section main frame and between the sides thereof, and meansfor manually adjusting the position of said l 8 frame independently ofsaid uid pressure means vfor positioning the frame within the operatingUNITED STATES PATENTS range of rectilinear movement of said pulley.Number Name Date l JOHN s. BELTZ. 1,317,997 Stuart oct. '1, 19191,663,344 Lennard Mar. 20, 1928 REFERENCES CITED? 1.770.934 Levin July22, 1930 The following references are of record in the ille of thispatent:

